Amplifying and oscillating tube with traveling wave control



Dec. 25, 1951 o. DOHLER EI'AL 2,530,007

- AMPLIFYING AND QSCILLATING TUBE WITH TRAVELING WAVE CONTROL Filed March 25, 1948 4 Sheets-Sheet l CaK Dec. 25, 1951 o. DOHLER ETAL 2,530,007

AMPLIFYING AND OSCILLATING TUBE WITH TRAVELING WAVE CONTROL 4 Sheets-Sheet 2 Filed March 2-5, 1948 Has/yrs Dec. 25, 1951 '0. D OHLER ETAL AMPLIFYING AND, OSCI 2,580,007 LLATING TUBE wrm TRAVELING WAVE-CONTROL Filed March 25, 1948 v 4 Sheets-Sheet 25 Dec. 25, 1951 0. DOHLER ETAL 2,580,007 AMPLIFYING AND OSCILLATING TUBE wrm TRAVELING WAVE CONTROL 4 Sheets-Sheet 4 Filed March 25, 1948 {W a fl n'rs d s/(me pal/Lem, #19122; #0194512 M. ex/v45;

\P ix Patented Dec. 25, 1951 UNITED STATES ATENT OFFICE AM PLIFY ING. AND OSCILLATING TUBE WITH A TRAVELING WAVE CONTROL Application March 25; 1948, Serial No. 16,974 In France April 21, 1947 7 Claims.

The present invention relates to electronic tubes of the travelling wave type, particularly for use as amplifiers and oscillators.

Electronic tubes are known, for example the travelling wave tubes described by Kom'pfner in "Wireless World" No. 52, November 1946, where an electronic beam moves in the field of a travelling wave at a velocity approximately equal to the phase velocity of the wave. It should 'be noted that the interaction between the electrons of the beam and the axial electric vector of the wave produces twoeliects:

l. A transfer of energy takes place' from the electrons to the wave. (The energy of the wave gradually increases as it is propagated.)

2; The electrons in the beam are brought together. (A pulsation of increasing density is produced along the beam.)

The travelling wave tubes of' the usual type make use only of the first of these two eiiects. The-objector the present inventionyis to produce' a tube in which the two effects are utilized simultaneously, which insures a better energy yield;

For this purpose the usual collector of the beam of electrons is preceded by a rhumbatron. In addition means are provided for permitting aggregation of the energy yielded to the rhumbatron and of the energy of the outlet guide or, if desired, means for coupling between the inlet and outlet guides.

The invention will be better understood by referring to the attached drawings, :in which:

Fig. l is a diagrammatic view of a first embodiment of the. invention;

Fig. 2 .is similar to Fig. 1 with. the addition of a coupling between the inlet and outlet of. the tube;

Fig. 3 is similar to Fig. 2 but with another form of couplingj and Fig. 4 is similar to Figs. 2 and 3 with a still further form of coupling. 7

In order to simplify the drawings, the tube has been shown in detail only in Figure 1; in the other figures certain of the details contained in the block b in Figure. l have been. represented by. a block having the same references with very schematic indication of the outline of the arrangement. Itshould be understood that ref-' erence is tobe made to the details of Figure 1 when considering the interior of the blockb in Figures 2-4. I

Fig. 1 shows the travelling wave tube t, the helix 0 of said tube in which said wave circulates, the beam of electrons f exchanging energy with the travelling wave and emitted by the cathode is, the inlet guide e and the outlet guide 81, and the rhumbatron cavities Cao which has a re-entrant portion with perforated walls as is designated at 0. The helix 0 is excited by means of the inlet guide e by any kind of generator (antenna, preceding stage, etc). Said helix acts both as a control system and as a grouping sys-, tem, by uniting two actions, viz. that of a velocity control circuit and that of .a grouping space in which the velocity modulation is changed to density modulation; as is known, these effectsare produced by the interaction of the travelling wave and the electronic beam. At the end of the control space the beam penetrates the rhumbatron. The electrons are braked therein and yield energy to the load coupled to the rhumbarton. Said energy is much greater than that transferred from the electrons to the wave in the control circuit or in an ordinary travelling wave tube (Without cavity). For, in the cavity, with. an appropriate adaptation to the load, the electrons are totally braked, but in the usual travelling wave tube the electrons lose only a small part of their energy corresponding tothe direct current potential. At the outlet of the control system and connected to the cavity are found the adaptation circuits or guides 31 and $2 of the load. As previously mentioned, the power produced in the cavity and also that produced by the grouping system are utilized at the same time. The two outlet leads are connected toa line or to a common guide u, a phase shifter with apiston core 02 in the path of one of the outlet guides producing the apprepria-te phase. By m isindicated the focussing coil; by h, the collector of the tube; and by'V, the'adjusting means of the cavity resonator (Car).

The. supplementary gain due to the addition of the cavity is large and selective. 'The gain up to the outlet guide 31 is small, having the same value over a wide range. The selectivity of the cavity may offer an advantage for selecting a narrow interval of a wide range of the common outlet guide. This advantage may be utilized for example for the transmission or, television to separate the. respective carrier. waves:

of: the image and. of thBwSOlll'l-d. Itis obvious that the union of the two outlet guides is not necessary. Two separate outlet guides may be provided, either one or both being utilized for the same purpose as indicated above.

It is moreover obvious that the invention need not be limited to the means shown in Fig. 1, even for this mode of embodiment. Any device producing the grouping of the electrons of a beam by interaction with a travelling electromagnetic wave is applicable (dielectric guide, delay line, etc.) The inlet "and outlet guides may of course be replaced by lines. The form given to the rhumbatrons in the figure is not limiting in any manner.

According to the invention a feed-back coupling may moreover be arranged between the inlet and outlet of the tube, which may go as far as auto-oscillation. The application of such a coupling (for the purpose of obtaining an oscillator with a wide control range) to an ordinary travelling wave tube by means of a resonant cavity does not form part of the invention, but the principle is close to it. Fig. 2 shows a travelling wave tube according to the invention, in which a coupling 1 between inlet and outlet guides is arranged which may be regulated by means of plunger pistons n. (The references analogous to Fig. 1 designate the same elements, which is also the case in the following figures.) Fig. 3 shows likewise a travelling Wave tube according to the invention, in which the coupling between inlet and outlet is effected by means of a tunable cavity K. By coupling the load to the cavity K, the properties of the control and grouping system are not influenced by the properties of the load. The coupling between-the cavity and the control system is slight, produced only by the electronic beam and not by impedances. The circuit arrangement of Fig. 3 represents an oscillator which is similar to the coupling oscillator known for lower frequencies; it possesses all the advantages of the latter as to the .independence of the frequency respecting the load and its coupling.

Fig. 4 shows still another embodiment of the invention based on a similar principle. In this case all the power yielded to the rhumbatron is 4 vantage is particularly important when the system is used for reception.

A second advantage is due to the fact that the control and grouping circuit possesses a large band width, of half a octave or more. Consequently, in a wide range it is sufficient to tune the outlet, i. e. the cavity. It is thus possible to use the system in an amplifier for radar scrambling. The wave to be scrambled can be received and amplified very rapidly by tuning only one circuit (the cavity resonator); after having found the wave, the density of the beam is modulated by means of disturbances applied to a grid 9 interposed between the cathode k and the control space (see Fig. 1).

What we claim is:

1. Ultra-short wave transmitting device comprising a travelling wave electron tube having means comprising a cathode and a collector provided with concentrating and biassing means for producing an electron beam propagating at a predetermined velocity between said cathode and said collector, a delay line extending parallel to the path of said electron beam, energizing means coupled with the input of said delay line for exciting a travelling wave therein, the said delay line being dimensioned in a predetermined manner so that the travelling wave propagation velocity is substantially equal to said electron velocity, whereby the beam current is radio-frequency controlled while the ultra-short wave energy is amplified along said delay line by interaction between the travelling wave and the beam, means comprising ultra-short wave conduit coupled with the output of said delay line for collecting ultra-short wave energy amplified therein, means comprising a cavity resonator coupled with said radio frequency controlled beam. between said delay line output and said collector for collecting said beam energy.

returned for feed-back coupling to the inlet of the helix or delay line. It is necessary to have large travelling wave amplitudes in order to obtain a good grouping of the electrons in spite of the space charge. The power yielded to the Working apparatus U, for example a horn, is tapped from the outlet of the delay line. Adaptations, diagrammatically represented by the pistons P1, P2, P3, are provided, particularly in order to obtain the amplitude and the appropriate phase in the cavity Cav. Thus there is obtained, as a distinct advantage over the preceding embodiments, a good grouping of the electrons owing to the large value of the electric field in the guide and'hence a large outlet power yielded to the working apparatus.

All the embodiments described offer in any case a definite advantage over the normal travelling wave tubes, namely the increase of output. As compared with the tubes of the klystron type, they offer in addition two important advantages, namely the following.

' First of all, the back-ground noise is much weaker. This effect is due to the. repeated and amplified interaction between the control field and the electrons and to the absence of a selective .and high Q circuit at the inlet. "This ad- 2. Tube as set forth in claim 1, wherein the cavity resonator has a re-entrant portion with perforated walls interposed on the path of the beam before the beam reaches the said collector.

3. Device as set forth in claim 1, comprising means coupled to said ultra short wave conduit and said means comprising a cavity resonator for combining energies collected respectively in the cavity resonator and at the output of said delay line.

4. Device as set forth in claim 3, comprising means coupled to said device for transmitting a portion of the combined energy to a load circuit and a feed-back coupling channel between the output and the input of said delay line for energizing said input by another portion of said combined output energy.

5. Devise as set forth in claim 3, comprising a branch conduit connected to said ultra-short wave conduits and means included with said branch conduit for regulating the length of said branch conduit for adjusting respective phases between the combined output energies.

6. Device as set forth in claim 1, comprising a feed-back coupling channel between the said output conduit and the input of said delay line for energizing said input by the energy collected at the output of said delay line, and a load circuit coupled to said cavity resonator conduit for absorbing the energy collected by said cavity resonaton' I r i 7. Device as set forth in claim 1 comprising afeed-back coupling channel between the said cavity resonator conduit and the input of said delay line for energizing said input by the energy collected by said cavity resonator, and a load circuit coupled to said delay line output conduit for absorbing the energy collected at the said output.

OSKAR DOHLER. HARRY HUBER. WERNER KLEEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS OTHER REFERENCES Article by Rudolph Kompfner, The Traveling Wave Tube as Amplifier at Microwaves, pp. 124- 127, inclusive, Proc. of I. R. E., vol. 35, No. 2, Feb. 1947.

Article by Kompfner, Proc. I. R. E., Feb. 1947. pp. 124-127, inclusive. 

